Softening of the bones caused by a deficiency of vitamin D, either from a poor diet or lack of sunshine or both is ________. A: osteoblast B: osteomalacia C: chondromalacia D: chondrogenesis

About bone formation, which is correct ( ) A: clavicle is formed by endochondral ossification B: cartilage mode is the first step C: cartilage lacular will enter osteoblast and osteoclast D: bone remodeling only occurs in baby

Paratfollicular cells or C cells of thyroid also secrete calcitonin, which has the function of ( ). A: Enhancing osteoblast activity B: Promoting the conversion of bone calcium into blood calcium C: Promoting calcification of bone tissue D: Reducing blood calcium E: Elevating blood calcium